Decoiler for wire and rod

ABSTRACT

A decoiler for delivery of wire or rod feed stock to a downstream production machine from a pre-formed coil. The decoiler includes an extended length rotatable mandrel adapted to extend along the interior of the coil such that the mandrel supports loops of the coil in hanging and slidable relation along the mandrel. At least a first feed head is disposed adjacent to the proximal end of the mandrel. The first feed head is adapted to feed the wire or rod feed stock from a rear loop of the coil outwardly in a curved path to form a spiral feed loop having a diameter greater than the coil. A variable height guide element is disposed at a position below the first feed head. The variable height guide element engages and follows an interior of the spiral feed loop to change height with a change in diameter of the spiral feed loop and to provide an output signal for speed control of the first feed head to maintain the diameter of the spiral feed loop within predefined limits.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application claims the benefit of, and priority from, U.S. Provisional Application 61/103,786 having a filing date of Oct. 8, 2008. The contents of this provisional application are hereby incorporated by reference as if fully set forth herein.

BACKGROUND

Wire and rod decoilers which are also referred to as uncoilers or prefeeders are well known to those of skill in the art. Such units are used in manufacturing environments to deliver lengths of previously coiled wire or rod stock to a production machine. By way of example only, such a production machine may be a header that applies cold forming to the wire or rod to produce articles such as screws, bolts or the like. In typical decoilers, coils of metal wire or rod stock are disposed in hanging relation around a large rotating cylinder referred to as a mandrel. Such mandrels are generally about 8 inches to 12 inches in diameter with a length of about 70 inches to about 140 inches. The coils of wire or rod stock are in the form of multiple stacked loops arranged in a compact helical configuration. The diameter of the loops is generally about 30 inches to about 60 inches. The stacked height of the coils is typically about 30 to about 70 inches long. Such coils typically weigh about 3,000 to about 7,000 pounds. Of course, larger or smaller coils may also be handled. The wire or rod stock handled by such decoilers is typically relatively heavy gauge having a diameter of about 0.625 inches to about 1.75 inches. The wire or rod may be round or polygonal in cross-section. As will be appreciated, such heavy gauge materials are relatively difficult to bend due to their substantial thickness. Thus, once such materials are coiled, they tend to retain a degree of inward curvature until forcibly straightened.

In typical prior decoilers, the production machine receiving the material from the decoiler applies a pulling force to the end of the wire or rod stock so as to pull the wire or rod stock away from the coil. As the wire or rod stock is pulled by the production machine, the coil diameter begins to cinch down. A bar coupled to a sensor extends through the interior of the coil such that when the coil is cinched inwardly beyond a pre-defined limit, the sensor activates a motor causing the mandrel and the supporting coil to rotate. This rotation introduces slack into the coil thereby offsetting the cinching caused by the pulling force applied by the production machine. The rate of rotation and the amount of run time are adjustable by the operator or may be controlled by a PLC or other programmable device.

In prior devices, there may also be a provision to further speed up the rotation when a tight coil is detected by a second sensor located closer to the coil axis. Such a second sensor may be used to loosen minor snags and to provide enhanced accuracy speed modulation. It is also generally known to provide a decoiler with an overrunning clutch which allows the production machine to pull the wire or rod stock in a substantially passive mode or at a rate faster than the decoilers mandrel is rotated. Inclusion of such an overrunning clutch smoothes variances between the speed of the decoiler and the rate of pulling by the production machine such that precise synchronization of the production machine and the decoiler is not required.

While the prior decoiling systems have worked well, the use of a rotating mandrel activated by a sensor as the mechanism used to feed wire away from the coil requires the mandrel to be activated and operated with a relatively high degree of precision to match with the pulling action of the production machine being fed. Moreover, these requirements must be satisfied in a system capable of handling large coil diameters and gauges and the weight and stiffness levels associated with such materials. Such devices are complex and relatively costly to produce and maintain. Another problem with prior systems has been in the pull-back of the wire or rod to the production machine. Specifically, the starting and stopping of the coil is translated to the production machine. This reflected inertia can cause the pinch rolls of the production machine to slip such that the lengths of wire drawn in may not be consistent. This is referred to as “short feeding” and may cause inconsistency in the final parts.

SUMMARY OF THE INVENTION

The present invention provides advantages and alternatives over the prior art by providing a decoiler adapted for the delivery of heavy gauge wire or rod stock which utilizes a feed head at the decoiler that collects and pushes the wire or rod feed stock outwardly from a main coil into an extended diameter feed loop rearward of the main coil. The enhanced diameter feed loop feeds to a conveyance path running to the production machine. An optional second feed head may be positioned along the conveyance path downstream from the first feed head to assist during initial system set up and to provide additional torque control if desired. A curvature adjustment unit that applies force selectively inwardly or outwardly may also be disposed along the conveyance path to assist in controlling curvature of the wire or rod during initial threading and/or pull back of the wire or rod. The diameter of the feed loop is monitored by a variable height guide element such as a dancer pulley or the like and the speed of the first feed head is adjusted to maintain that diameter within desired limits thereby maintaining a supply of wire or rod material to the production machine at a desired rate.

According to one potentially desirable aspect, the present invention provides a decoiler for delivery of wire or rod feed stock to a downstream production machine from a pre-formed coil having a plurality of loops in interconnected helical relation. The decoiler includes an extended length mandrel having a proximal end and a distal end. The mandrel is adapted to extend along the interior of the coil such that the mandrel supports loops of the coil in hanging and slidable relation along the mandrel. A first feed head is disposed adjacent to the proximal end of the mandrel. The first feed head is adapted to feed the wire or rod feed stock from a rear loop of the coil outwardly in a curved path to form a spiral feed loop having a diameter greater than the coil. The first feed head has adjustable speed control. A variable height guide is positioned below the first feed head, the variable height guide is adapted to engage an interior of the spiral feed loop and to change height with a change in diameter of the spiral feed loop. The speed of the first feed head is adjusted in response to the position of the variable height guide such that the diameter of the spiral feed loop is maintained within a predefined range.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

FIG. 1 is a perspective view of an exemplary decoiler for heavy gauge wire or rod stock consistent with the present disclosure;

FIG. 2 is a schematic view of an exemplary feed system utilized in the decoiler of FIG. 1; and

FIG. 3 is a schematic view of a vertical force applicator for curvature adjustment along the travel path of the wire or rod stock.

While an exemplary configuration has been illustrated and will hereinafter be described in detail, it is to be understood that in no event is the invention to be limited to such embodiments and practices as may be illustrated and described herein. On the contrary, it is intended that the present invention shall extend to all alternatives and modifications as may embrace the general principals of the invention within the full spirit and scope thereof.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Reference will now be made to the drawings wherein, to the extent possible, like reference numerals are utilized to designate like elements in the various views. In FIG. 1, a decoiler 12 is illustrated conveying an elongated wire or rod 14 to the input of a production machine 16 such as a header or other machine that applies shaping by stamping, drawings, cutting or the like as will be well known to those with skill in the art. The production machine 16 typically applies a pulling force to the wire or rod 14 to draw in a desired length of material for the subsequent forming operation. The decoiler 12 of the present invention augments the pulling force of the production machine 16 by providing a supply or reservoir of the wire or rod 14 in a low-tension state which may be readily pulled towards the production machine 16 without undue effort or interruption.

In the exemplary illustrated configuration the decoiler 12 includes a cabinet body 20 for housing drives and instrumentation. The main frame of the decoiler 12 is mounted on skids 22 or other support structures as may be desired to facilitate portability by use of a forklift or other suitable device. A drive box 26 housing drives and supporting rotating elements as will be described further hereinafter is mounted at the cabinet body 20.

As illustrated, a cantilever frame 28 projects outwardly away from the drive box 26 and supports an elongated rotatable mandrel 30 in extended orientation relative to the floor. The mandrel 30 is typically about 8 inches to about 12 inches in diameter and about 70 to about 140 inches long, although larger and smaller sizes may be used as desired. The mandrel 30 preferably includes a relatively low friction durable metal surface and is rotatable in both clockwise and counter clockwise directions by operation of a drive 32 (FIG. 2) housed at the drive box 26.

As shown, the cantilever frame 28 and the mandrel 30 extend through the interior of a helical multi-loop coil 34 of wire or rod feed stock material such that the loops of the coil hang down from the mandrel 30. While a coil 34 having only a small number of loops is illustrated for explanatory purposes, it is to be understood that in practice the coil 34 may incorporate a large number of loops and occupy a substantial percentage of the length of the mandrel 30 with the loops of the coil 34 hanging down from the mandrel 30 towards to floor as shown. The coil 34 is thus slidable relative to the surface of the mandrel 30.

By way of example only, and not limitation, the wire or rod 14 forming the coil 34 may be a ferris or nonferris metal including copper, brass, aluminum, low-alloy steel, or the like. Such materials may be round or polygonal in cross-section and will typically have a diameter of about 0.625 inches to about 1.75 inches, although larger or smaller diameters may be used as well. Non-metallic materials such as fiber reinforced plastics and the like that are capable of coiling and uncoiling may likewise be utilized if desired.

Referring jointly to FIGS. 1 and 2, the illustrated exemplary decoiler 12 includes a first feed head 36 in the form of a feed roller which may be rotated in conjunction with rotation of the mandrel 30. As shown, during operation, the first feed head 36 engages a rear loop 38 of the coil 34. As will be appreciated, this arrangement is achieved by threading the tail end of the coil 32 through the first feed head 36 and along a desired conveyance path before commencing operation. Of course, other feed head configurations capable of engaging and expelling the wire or rod 14 may be used if desired.

In the illustrated arrangement, concurrent rotation of the first feed head 36 and the mandrel 30 in the same direction causes the wire or rod 14 to be pushed outwardly in a lateral direction away from the first feed head 36. Due to the prior coiled configuration of the wire or rod 14, the wire or rod 14 exits the first feed head 36 along a generally downward and inwardly curving path as shown. The travel path for the wire or rod 14 exiting the first feed head extends downwardly and around a variable height guide element 40 such as a dancer pulley or the like which may be disposed in substantially aligned relation with the first feed head 36 at a position below the mandrel 30. As shown, after passing below the variable height guide element 40, the wire or rod 14 continues upwardly in an inwardly curving path towards the first feed head 36. The upwardly curving portion of the wire or rod 14 then passes over a transition shoe 42 (FIG. 2) in the form of a curved smooth surface ramp disposed behind or above the first feed head 36. Upon exiting the transition shoe 42, the wire or rod 14 then passes along a generally linear feed path oriented transverse to the axis of the coil 34 for discharge towards the production machine 16.

In the illustrated arrangement, the portion of the wire or rod 14 exiting the first feed head 36 forms a spiral feed loop 44 running from the first feed head 36 below the variable height guide element 40 and up to the linear feed guide 42 in a substantially 360 degree pattern. As illustrated, the spiral feed loop 44 has a diameter which is substantially greater than the diameter of the loops forming the coil 34. The spiral feed loop 44 provides a reservoir or buffer of available wire or rod 14 to be pulled into the production machine 16. The variable height guide element 40 may move up and down in following relation to a change in height of the adjacent wire or rod. Thus, by tying the variable height guide element 40 to a control monitor, the diameter of the spiral feed loop and thus the amount of wire or rod feed stock between the first feed head 36 and the transition shoe 42 can be monitored and controlled.

In operation, the speed of the first feed head may be adjusted to control the amount of material in the spiral feed loop 44. In this regard, an increase in the speed of the first feed head 36 will tend to provide a corresponding increase in the diameter of the spiral feed loop 44. Likewise, slowing down the first feed head will cause the diameter of the loop 44 to decrease as the wire or rod 14 is pulled into the production machine 16. Thus, by tying the variable height guide element 40 to a controller such as a PLC, drive control or the like as will be well known to those of skill in the art, the speed of the first feed head 36 can be varied during operation to maintain a desired reservoir of available wire or rod within pre-defined limits. Specifically, if the position of the variable height guide element 40 indicates that the spiral feed loop 44 is becoming too small, this indicates that the production machine 16 is pulling the wire or rod 14 at a faster rate than the rate of discharge by the first feed head 36. In this situation, the controller can increase the speed of the first feed head 36 until a diameter corresponding to a desired level of material within the spiral fed loop 44 is achieved and maintained. Likewise, if the position of the variable height guide element 40 indicates that the spiral feed loop 44 is becoming too large, this indicates that the production machine 16 is pulling the wire or rod 14 at a slower rate than the rate of discharge by the first feed head 36. In this situation, the controller can decrease the speed of the first feed head 36 until a diameter corresponding to a desired level of material within the spiral fed loop 44 is obtained and maintained. Thus, a predefined reservoir of available material can be maintained. Of course, manual speed adjustment may also be used if desired. In practice it may be desirable to preset a desired range for the diameter of the spiral feed loop 44 with high and low limits such that any diameter within that range is acceptable. Thus, an instruction to adjust the speed of the first feed head is issued only when the diameter is outside these limits. As will be appreciated, while a single spiral feed loop 44 is illustrated, a pattern using two or more enhanced diameter feed loops between the first feed head 36 and the linear feed guide 42 also may be used if desired.

The travel path for the wire or rod 14 passing through the first feed head 36, around the variable height guide element 40 and into the linear pathway for delivery to the production machine 16 is initially established by manually threading up the decoiler with the wire or rod 14 in the desired pattern prior to commencing operation. As will be appreciated, achieving the illustrated pattern for the spiral feed loop 44 is aided by the pre-established inward curvature of the previously coiled wire or rod 14. However, this curvature also makes the conversion to a linear travel path more difficult since the wire or rod 14 tends to bend inwardly. Moreover, when working with relatively heavy gauge wire or rod stock, the stiffness of the material may make the threading operation difficult. Finally, in some instances, it may be desirable to apply extra torque along the feed path of the wire or rod 14 to facilitate delivery to, or retraction from, the production machine.

As best illustrated through joint reference to FIGS. 1 and 2, in the illustrated and potentially preferred arrangement, the decoiler 12 includes an optional second feed head designated generally as 50. The second feed head 50 includes an upper roller 52 and a lower roller 54 (FIG. 2). The upper roller 52 may be moved towards and away from the lower roller 54 so as to selectively grip and release a portion of the wire or rod 14 downstream of the transition shoe 42. Of course, any other selectively engageable feed head arrangement may likewise be used as desired.

In typical practice, during the initial thread up procedure between the decoiler 12 and the production machine 16, the second feed head 50 is used to engage the wire or rod 14 and to apply a torque to pull the wire or rod 14 along the travel path. This torque application reduces the manual force needed to feed the wire or rod 14 through a pair of final straightening rolls 56, 58 to the production machine 16. Under normal operating conditions, once the initial threading up procedure has been completed, and the wire or rod has been gripped by the production machine, the second feed head 50 may be disengaged from gripping the wire or rod. Thereafter, the torque is applied primarily by the pulling action of the production machine 16 with feed supply provided by the first feed head 36.

It is also contemplated that the second feed head 50 may remain engaged with the wire or rod 14 during operation if desired. By way of example only and not limitation, operating the decoiler 12 while maintaining torque-applying engagement between the second feed head 50 and the wire or rod may be desirable in situations where the production machine is unable to independently provide an adequate pulling force to draw the available wire or rod away from the decoiler 12. In such an operating mode, the second feed head provides supplementary torque to the system. In this operating mode, the feed rate of the second feed head will preferably be substantially matched to the production machine.

As noted previously, the wire or rod 14 tends to retain an inward curvature due to prior coiling. In order to counteract this tendency, the illustrated exemplary apparatus includes a force-applying curvature adjustment unit designated generally 60 which is best seen in FIGS. 2 and 3. In the illustrated exemplary configuration, the curvature adjustment unit 60 is positioned in adjacent downstream relation to the exit of the transition shoe 42 and upstream from the second feed head 50. The curvature adjustment unit 60 is adapted to apply inward or outward bearing force against the wire or rod 14 to straighten or otherwise adjust the curvature of the wire or rod.

Referring to FIGS. 2 and 3, in the exemplary arrangement, the curvature adjustment unit 60 includes a pair of spaced rollers including a lower roller 62 and an upper roller 64 held in fixed, spaced relation relative to one another along a sleeve 66. The sleeve 66 is, in turn, held in moving relation along a guide post 68. In operation, axial drive units 70 may be used to move the sleeve 66 to various positions along the length of the guide post 68. Thus, the height of the rollers 62, 64 can be adjusted relative to the linear travel path of the wire or rod 14 exiting the transition shoe 42. The adjustment in height of the rollers 62, 64 may be used to apply an upward or downward biasing force against the wire or rod 14.

According to one exemplary practice, during the initial threading up procedure and subsequent normal operation, the sleeve 66 is held at a position such that the lower roller 62 is biased against the underside of wire or rod 14 so as to apply an upward force. This outward biasing force relative to the natural curvature of the wire or rod 14 aids in establishing and maintaining a linear travel path out of the decoiler 12 and towards the production machine 16. It may also reduce the torque requirement for withdrawal of wire or rod 14.

As noted previously, the travel direction of the wire or rod 14 may be reversed if desired to recover an unused portion of the wire or rod 14. This direction reversal may be carried out by reversing the direction of rotation of the mandrel 30, the first feed head 36 and the second feed head 50 if utilized. In this regard, it may be desirable to engage the second feed head 50 during recovery to provide additional torque for the recovery. During the recovery procedure, it may also be desirable to lower the sleeve 66 such that the upper roller bears against the wire or rod 14 thereby pressing inwardly. This inwardly applied force tends to reintroduce a degree of inward curvature to aid in the recoiling operation.

In light of the prior description of components, the exemplary operation of the decoiler 12 will now be described. In this regard, a preformed coil 34 of wire or rod is loaded in hanging relation about the rotatable mandrel 30 and the cantilever frame 28 supporting the mandrel. A sensor bar 82 extends from a distal end of cantilever frame 80 through the interior of the coil 34. With the coil 34 in place, the tail end of the coil is threaded through the first feed head 36 and in a spiral path traveling below the variable height guide element 40 and up to the transition shoe 42 for transition from a curved travel path to a substantially linear travel path. During the threading operation, the lower roller 64 of the curvature adjustment unit 60 is positioned at a height to provide lower support and to impart a slight upward biasing force outward from the normal curvature path. This upward applied force facilitates linear travel away from the transition shoe 42. Following the curvature adjustment unit 60, the wire or rod 14 passes through the second feed head 50. During the initial thread up, the second feed head 50 engages and applies torque to the wire or rod 14. The wire or rod 14 is then threaded through the final straightening rolls 56, 58 for delivery to the production machine 16.

Once initial threading has taken place, the decoiler 12 may be operated in a so called “automatic run” mode. In this automatic run mode, the production machine 16 pulls lengths of the wire or rod 14 away from the spiral feed loop 44 either with or without involvement of the second feed head 50 while the first feed head 36 simultaneously delivers wire or rod from the main coil 34 into the spiral feed loop 44. During the automatic run mode, the position of the vertical height guide element 40 is continuously monitored as an indicator of the diameter of the spiral feed loop 44. The speed of the first feed head 36 is adjusted to maintain the diameter of the spiral feed loop within a desired range. The feed rate of wire or rod 14 into the spiral feed loop is thereby substantially matched to the demand rate of the production machine. In the event that the main coil begins to cinch or kink, the sensor bar will be raised, thereby activating a shut-off or warning indicator to permit necessary adjustment.

Once the production machine 16 has no need for additional wire or rod 14, the optional second feed head 50 engages the wire or rod 14 and the rotation of the mandrel 30, the first feed head 36, and the second feed head 50 are reversed to draw the wire or rod 14 back into the decoiler for recoiling. During this recoiling procedure, the curvature adjustment unit 60 is lowered such that the upper roller 64 presses down against the wire or rod 14 to reintroduce a degree of inward curvature and to facilitate recoiling.

The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context. 

1. A decoiler for delivery of wire or rod to a downstream production machine from a pre-formed coil having a plurality of loops in interconnected helical relation, the decoiler comprising: an extended length mandrel having a proximal end and a distal end, the mandrel being adapted to extend along the interior of the coil such that the mandrel supports loops of the coil in hanging and slidable relation along the mandrel; a first feed head disposed adjacent to the proximal end of the mandrel, the first feed head adapted to feed the wire or rod from a rear loop of the coil outwardly in a curved path to form a spiral feed loop having a diameter greater than the coil, the first feed head having adjustable speed control; a variable height guide disposed at a position below the first feed head, the variable height guide adapted to engage an interior of the spiral feed loop and to change height with a change in diameter of the spiral feed loop, wherein the speed of the first feed head is adjusted in response to the position of the variable height guide such that the diameter of the spiral feed loop is maintained within a predefined range.
 2. The decoiler as recited in claim 1, wherein the extended length mandrel is rotatably supported on a cantilever frame adapted to extend longitudinally through the interior of the coil.
 3. The decoiler as recited in claim 2, further including a sensor bar extending longitudinally through the interior of the coil, the sensor bar adapted to activate shut-down of the decoiler upon cinching of the coil.
 4. The decoiler as recited in claim 3, wherein the sensor bar extends from a distal end of the cantilever frame towards the rear loop of the coil.
 5. The decoiler as recited in claim 1, wherein the first feed head includes a roller having a channel adapted to grip the wire or rod.
 6. The decoiler as recited in claim 1, further including a feed guide comprising a curved transition shoe adapted to collect the wire or rod exiting the spiral feed loop and to deliver the wire or rod along a substantially linear travel path transverse to a longitudinal axis of the coil.
 7. The decoiler as recited in claim 6, wherein the curved transition shoe is disposed behind the first feed head.
 8. The decoiler as recited in claim 1, wherein the variable height guide comprises a dancer pulley.
 9. The decoiler as recited in claim 8, wherein the variable height guide is adapted to provide a position output signal.
 10. A decoiler for delivery of wire or rod to a downstream production machine from a pre-formed coil having a plurality of loops in interconnected helical relation, the decoiler comprising: an extended length mandrel having a proximal end and a distal end, the mandrel being adapted to extend along the interior of the coil such that the mandrel supports loops of the coil in hanging and slidable relation along the mandrel; a first feed head disposed adjacent to the proximal end of the mandrel, the first feed head adapted to feed the wire or rod from a rear loop of the coil outwardly in a curved path to form a spiral feed loop having a diameter greater than the coil, the first feed head having adjustable speed control; a variable height guide disposed at a position below the first feed head, the variable height guide adapted to engage an interior of the spiral feed loop and to change height with a change in diameter of the spiral feed loop, wherein the speed of the first feed head is adjusted in response to the position of the variable height guide such that the diameter of the spiral feed loop is maintained within a predefined range; a feed guide adapted to collect the wire or rod exiting the spiral feed loop and to deliver the wire or rod along a substantially linear outbound travel path transverse to a longitudinal axis of the coil; at least a second feed head disposed downstream from the feed guide along the outbound travel path, the second feed head adapted to selectively engage the wire or rod in torque applying relation to assist in conveyance of the wire or rod, each of the first feed head, the second feed head and the mandrel being rotatable in both clockwise and counterclockwise directions.
 11. The decoiler as recited in claim 10, wherein the feed guide comprises a curved transition shoe adapted to collect the wire or rod exiting the spiral feed loop and to deliver the wire or rod along a substantially linear travel path transverse to a longitudinal axis of the coil.
 12. The decoiler as recited in claim 11, wherein the curved transition shoe is disposed behind the first feed head.
 13. The decoiler as recited in claim 10, wherein the variable height guide comprises a dancer pulley.
 14. The decoiler as recited in claim 13, wherein the variable height guide is adapted to provide a position output signal.
 15. A decoiler for delivery of wire or rod to a downstream production machine from a pre-formed coil having a plurality of loops in interconnected helical relation, the decoiler comprising: an extended length mandrel having a proximal end and a distal end, the mandrel being adapted to extend along the interior of the coil such that the mandrel supports loops of the coil in hanging and slidable relation along the mandrel; a first feed head disposed adjacent to the proximal end of the mandrel, the first feed head adapted to feed the wire or rod from a rear loop of the coil outwardly in a curved path to form a spiral feed loop having a diameter greater than the coil, the first feed head having adjustable speed control; a variable height guide disposed at a position below the first feed head, the variable height guide adapted to engage an interior of the spiral feed loop and to change height with a change in diameter of the spiral feed loop, wherein the speed of the first feed head is adjusted in response to the position of the variable height guide such that the diameter of the spiral feed loop is maintained within a predefined range; a feed guide adapted to collect the wire or rod exiting the spiral feed loop and to deliver the wire or rod along a substantially linear outbound travel path transverse to a longitudinal axis of the coil; a selectively engaged curvature adjustment unit disposed downstream of the feed guide along the outbound travel path, the curvature adjustment unit comprising a pair of force application rollers, the force application rollers held in fixed, spaced relation to one another on opposing sides of the outbound travel path, the force application rollers being moveable along a line in transverse relation to the outbound travel path to selectively apply inward or outward bending force to the wire or rod.
 16. The decoiler as recited in claim 15, wherein the force application rollers are supported on a moveable sleeve mounted on a guidepost.
 17. The decoiler as recited in claim 16, further including at least a second feed head disposed downstream from the curvature adjustment unit along the outbound travel path, the second feed head adapted to selectively engage the wire or rod in torque applying relation to assist in conveyance of the wire or rod, each of the first feed head, the second feed head and the mandrel being rotatable in both clockwise and counterclockwise directions.
 18. The decoiler as recited in claim 17, wherein the variable height guide comprises a dancer pulley.
 19. The decoiler as recited in claim 18, wherein the variable height guide is adapted to provide a position output signal. 